Reaction of hexafluorothioacetone dimer with indoles, pyrroles, furans and thiophenes

Abstract Reaction of indoles with 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietane 1 in the presence of CsF catalyst led to the rapid and high yield formation of indoles bearing a SCH(CF 3 ) 2 group in the 3-position. The same reaction carried out in the absence of catalyst unexpectedly resulted in the formation of indoles bearing a C(CF 3 ) 2 S 2 CH(CF 3 ) 2 group in the 3-position. Pyrrole, 2-Ethyl-1H-pyrrole and 2,4-dimethyl-1H-pyrrole were found to be more reactive toward 1 , giving the corresponding 1:1 adducts, while both furan and thiophene were not active toward 1 even at elevated temperature. Activated 2,3-dimethylfuran gave the corresponding 1:1 adduct in the reaction with 1 , while both 2,5-dimethylfuran and 2,5-dimethylthiophene reacted with 1 at elevated temperature giving the corresponding ene-products.